Heat exchanger



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Aug. 5, 1958 K. BERG EIAL 72,846,197

' HEAT EXCHANGER Filed April 16, 1952 2 Sheets-Sheet 1 pr/or Qrf K. BERG ETAL HEAT EXCHANGER 2 Sheets-Sheet 2 4/7 adj fa? 1720?! Aug. 5, 1958 Filed April 16, 152

United States Patent HEAT EXCHANGER Knut Berg, Saltsjobaden, Olle Ahlin, Stockholm, Sweden, and Harry Lindqvist, deceased, late of Stockholm, gwetllen, by Elin Lindqvist, administrator, Stockholm,

we en Application April 16, 1952, Serial No. 282,564

3 Claims. (Cl. 257-245) The present invention relates to an improved heat exchanger having a number of parallelepipedic shaped channels arranged on top of each other, intended for heat exchanging medium in adjacent channels defined by parallel plates supported in parallel spaced relation in a frame work by means of a number of elongated supporting rods and spacer elements.

In manufacturing such heat exchangers it is already known to close the parallelepipedic. shaped channels along their side edges with impregnated wooden ribs. These are arranged as spacer elements along the side edges of the channels, and are provided with longitudinal ridges which serve as a support in the assembly of the outside rim (by means of which rim the plates have earlier been joined by hand). Cylindrical pieces of cut tubes are used as spacer elements in the channels. As may be noted in Figure l of the accompanying drawings, showing a vertical section of a conventional heat exchanger, in every other channel a cylindrical tube is disposed between the rods of the intermediate channels. This known apparatus has several disadvantages. In the first place leaks are likely to occur, especially between the corners of each two mutually adjacent channels. These adjacent channels convey two diiferent media, between which is intended that heat should be exchanged indirectly through the surfaces of the channels. Direct mixing of the two media must not take place. In conventional practice it is necessary to contend with the disadvantage that the cylindrical spacer elements press against the plates, thus damaging the plates lying between. Finally the known folding-over of enclosed rods takes time. The invention relates to an embodiment of a heat exchanger where these and other disadvantages are eliminated.

The invention primarily contemplates a heat exchanger in which the channels consist of plates joined along their side edges, said plates being joined by a rim or fold in such a manner that at least one plate edge is doublefolded into the other in a recessed or counter-sunk part thereof, and that the spacer elements in each channel corner are shaped as plane blocks having a right angle which is nested in the channel corner, and preferably provided with recesses for receiving the rim fold (folds). Other spacer elements are shaped as spacer tubes. A modification of the invention is contemplated wherein the two plate edges are double-folded into each other and wherein the surface of the plane corner block contacting the rim is provided with corresponding recesses to receive the fold.

The surfaces of the plate edges contacting each other, according to another modification, are provided with a coating of an adhesive sealing material.

Another feature of the invention is characterized in that the edges of the end surfaces of the spacer tubes contacting the channel plates are rounded and that the spacer tubes have been especially softened before their insertion between the channel plates.

The invention will now be described in greater detail in the following specification which refers to the accompanying drawings, in which,

Figure 1 shows a vertical section of a heat exchanger of a known type;

Figure 2 shows a vertical section of a heat exchanger made according to the invention;

Figure 3 shows a horizontal section of a corner between two channels;

Figure 4 shows a perspective of the corner blocks, and

Figures 5 and 6 show two. types of rim assemblies for joining the plates forming the channels.

In Figure l a conventional heat exchanger is illustrated comprising three channels designated A, B and C. Plates 1 and 2 thus form channel C, and plates 4 and 7 form channel A. Closure of the channels A and C is effected over the rods 19, 13 respectively, each formed with an angular ridge and extending along the full length of the channel and constituting permanent spacer elements. The interior spacer elements consist of cylindrical tubes 20, 3, and 22, 6 respectively. In channels A and C the direction of flow of the medium is perpendicular to the plane of the drawing. In channel B another medium flows in the plane of the drawing, e. g. from the right to the left. Fig. 1 shows the spacer elements as consisting of cylindrical tubes 3 and 17 respectively. In the channel B each cylindrical tube will thus always contact the plate surfaces 2 and 4 respectively. This means that the tubes, when expanded by heat, rub against the plate resulting in damage and leakage. The assembling and sealing of the channel A will also be difficult because the thicker plate 7 is to be joined to the thinner channel plate 4. In the drawing, number 12 designates a part of the frame work and 8, 10 and 9, 11 respectively the elongated supporting rods with their locking nuts for joining the channels. Reference numeral 18 designates the sloping end surface of the rod in channel B.

In accordance with the present invention as shown in Fig. 2, the channels A, B, C and D are defined by plates 21, 22, 23 and 26. The thicker covering plate 26, as shown in Fig. 2, is folded as indicated at 38. It is fixed in its position in relation to the angle bar 36 by means of rivets 37. The designations 24, 25 and 34, 35 respectively correspond to supporting rods and nuts for joining the channels A, B, C, D etc. According to the invention there are disposed in all corners of the channels, blocks 39, 40, 41, 42. The shape of these blocks is evident from Figure 4, each block having one right angle for nesting or fitting in the corner. In Figure 3 is shown the arrangement of the blocks in two mutually adjacent channels.

The full lines 46, 47 show the outline of the blades mounted in the channels B and D and broken lines 45, 48 show the outline of the blocks mounted in channels A and C. In the channels B and D the medium enters the channel in the plane of B drawing from above as seenin Fig. 3 with the direction of flow downwards. In the channels A and C the direction of flow is from the right to the left (likewise in the plane of the drawing). As is evident from Figure 4 the blocks have their side walls 46, 47 and 48, 45 respectively receding in the direction of flow of the medium and have recesses 53, 54 for receiving the rim fold (folds). The blocks are provided with corresponding apertures 49 for the supporting rods 34. Except the channel corners, the other spacer elements according to the invention consist of cylindrical spacer tubes, designated 28, 29, 30 in Figure 2. According to the invention, the edges of the end surfaces of the spacer tubes contacting the channel plates are rounded, as indicated by reference numeral 27. Furthermore the spacer tubes have been especially softened before their insertion between the channel plates. In manufacturing a heat exchanger according to the technical de scription given above, it is possible to utilize thinner plates compared to the plates of the conventional apparatus which must be sufficiently strong to resist damage to the plates caused by conventional spacer elements. By utilizing a thinner plate material it is easier to form joints where one plate edge, by means of a rim fold, is double-folded into a counter-sunk part of the other, giving a so-called Pittsburg-rirn which provides a sufiicient stifiening of the rim to guard against deformation. Furthermore, it is possible to increase the air-tightness of the rims by providing the plate edges 57, 5'9, 61 and 58, 63 and 56, 67 and 68, 66 respectively with a coating 62 of an adhesive and sealing material. An especially convenient material for this purpose has proved to be the so-called Araldit. Coatings consisting of aluminum powder suspended in water glass have been tested and found useful in this invention. The dotted lines 60, 64 and 65 (see Figures 5 and 6) are intended to show different phases in closing of the joints.

The manufacture of the rims joining the channel plates is carried out so that one channel plate, by means of a so-called Pittsburg-machine, is provided with a Pittsburg-rim. The other corresponding channel plate is put in an edge press and is formed with an angular single rim. The two plates are then put together and, after coating with an adhesive and/or sealing material, the tongue (dotted in Figure 5) is bent down. By using the type of rim here proposed, the joined may be made without using reaction or counter pressure. This is, as indicated above, dependent upon the'fact that sufficient stiffening is obtained by such a rim. The manufacture of a heat exchanger according to the invention thus results in a saving of labor as compared with manufacturing of the conventional constructions.

We claim:

1. In a heat exchanger comprising a series of spaced parallel plates defining a plurality of superimposed openended channels, the adjacent plates of said series having corresponding pairs of their opposite edges interfolded upon each other for their entire length to provide fluid tight seams along the entire length of opposite sides of said channels terminating at the open ends of said channels, and the edge portion of one of said adjacent plates being inwardly offset at said seam to form a recess in which the seam is disposed to provide a rigid structure having substantially plane side surfaces, and a spacer element disposed between adjacent plates at each corner 4 only thereof inwardly of said seams and adjacent the seam terminal end portions in fluid tight engagement with the opposite surfaces of adjacent plates operable to prevent leakage between adjacent channels at the corners of said plates, said elements having a recess for said inwardly oflset seam portion of said plates.

2. A heat exchanger according to claim 1 wherein the marginal edge portions of said adjacent plates are each formed with reverse folds and are interlocked to provide the seam.

3. In a heat exchanger comprising a series of spaced parallel plates defining a plurality of superimposed openended channels, the adjacent plates of said series having corresponding pairs of their opposite edges interfolded upon each other for their entire length to provide fluid tight seams along the entire length of opposite sides of said channels terminating at the open ends of said channels, and the edge portion of one of said adjacent plates being inwardly offset at said seam to form a recess in which the seam is disposed to provide a rigid structure having substantially plane side surfaces, a spacer element disposed between adjacent plates at each corner only thereof inwardly of said seams and adjacent the seam terminal end portions in fluid tight engagement with the opposite surfaces of adjacent plates operable to prevent leakage between adjacent channels at the corners of said plates, said elements having a recess for said inwardly offset seam portion of said plates, and other spacer elements in the interior of said channels spaced inwardly of said channels from said first mentioned spacer elements comprising tubular members composed of softened material and having their end edges rounded at the points of contact with said adjacent plates.

References Cited in the .file of this patent UNITED STATES PATENTS 1,734,956 Baldwin a- Nov. 12, 1929' 2,076,228 Dressing Apr. 6, 1937- 2,576,845 McDonald Nov, 27, 1951 FOREIGN PATENTS 56,514 Sweden Mar. 21, 1921 29,315 France Mar. 24, 1925 (Addition to No. 580,039) 635,300 France Dec. 27, 1927 890,014 France Oct. 25, 1943 

